Q: Thankyou for years of informative and helpful information through your column. Could you suggest a powder and loads for my 1886 BSA Martini-Henry Mk III in .577/450? I have on hand 410gn cast lead alloy gas-check projectiles and new Starline cases. Barrel length is 640mm. When I got it, the rifle was a basket case with the last 15cm of the barrel in very poor condition. I had it shortened, re-crowned and new foresight installed. I’m waiting impatiently for new stock work. Could you also suggest loads for my Ruger No. 3 in .45-90? I had it rechambered for this cartridge. I used Hornady 325gn FTX projectiles when it was a .45-70 and have some left over.
A: In the .577/450 Martini Henry 38gn of AR2207 drives a 410gn lead bullet at 1435fps with 1206 ft/lb of muzzle energy. The only loads that I have for the .45-90 Winchester are for lead bullets. What may be a mild load in your Ruger is 52gn of AR2207 with a 385gn lead bullet which gets 2080fps and churns up 3699ft/lb of energy. If you want to go as heavy as a 500gn lead bullet, 48gn of AR2207 gets about 1770fps and 3479 ft.lbs. These loads were intended for old Sharps and lever-action rifles and develop low chamber pressures of around 25,000 to 26,000 psi, but even though your rifle could safely contain double that amount of pressure, I am not too sure that your .45-90 cases could safely handle pressures that high. As for the Hornady 325gn FTX projectile: I suggest you work up from the load you used in your rifle when it was in .45-70. For your .45-90 I recommend you get some of the black-coated lead bullets made by Hawkesbury River.